Provided is a technique capable of preventing a deterioration of a frame rate or a temporal resolution and estimating a blood flow velocity in a wide velocity range. A method is based on an unequal interval transmission method, and calculates a blood flow velocity by using a temporally adjacent received signal set and a temporally discontinuous received signal set, among a plurality of received signals obtained via a plurality of times of transmission in one transmission direction. When a number of the adjacent received signal set and a number of the temporally discontinuous received signal set are the same, an expansion of the velocity range similar to an unequal interval transmission in related art can be realized and the frame rate can be improved.
